1. Technical Field
The present invention relates to a meteorological observation system and, more particularly, to a meteorological observation system using vehicles.
2. Description of the Related Art
As a vehicle has recently emerged as one of the essential goods of life as well as the industrial world, traffic accidents very frequently occur due to a sudden increase of the vehicles globally, Accordingly, the improvement of safety of the vehicle has emerged as an important issue.
A passive type vehicle safety system using air bags and safety belts for minimizing damage attributable to traffic accidents is gradually changed to an active type vehicle safety system using an Automatic Braking System (ABS), a vehicle-to-vehicle distance alarm system, and side/rear surveillance radars capable of preventing an accident.
The International Telecommunication Union Radiocommunication sector (ITU-R) recommends several items related to Transport Information and Control Systems (TICS). TICS is a system in which computer, communication, location information and vehicle technologies integrated in order to improve the safety and efficiency of a ground traffic system and a method of operating the ground traffic system.
An Advanced Vehicle Control Systems (AVCS) that belongs to TICS and that relates to the direct driving of a vehicle has several points required to prevent a collision. A radar for a vehicle is one of technologies that may be applied to the safe driving of a vehicle through the assistance of a driver.
A radar for a vehicle using a radar was commercialized in Japan in the early 1980s, but the radar was too sensitive to several weather conditions (e.g., vulnerable to contamination, such as soil and dust). Accordingly, a method using millimeter waves is widely used. Active researches is carried out on a radar for a vehicle using millimeter waves is characterized in that the radar has relatively small errors and may be easily used even in several weather conditions in terms of its application. Millimeter waves mean electromagnetic waves whose frequency wavelength is a millimeter unit of 30 to 300 GHz.
A band of 24 GHz for the near/middle distance is partially used in a radar sensor for detecting the front using millimeter waves, but active researches is carried out on a radar sensor for detecting the front, which has a band of 77 GHz for the long distance (e.g., a maximum of about 200 m). In relation to standardization, ITU Radiocommunication Assembly (RA-2000) in Turkey on May, 2002 recommended bands of 60 GHz and 76 GHz for a radar for a vehicle. In Korea, in accordance with Article 9 of Radio Regulation Law on April, 2001, Notification No. 2001-21 of the Ministry of Information and Communication has distributed and announced a band of 76 to 77 GHz into frequencies for a vehicle radar for a specific small-output radio station. Today, a technical reference guideline for a radar for detecting the front in Korea has been provided.
Furthermore, the frequencies of several bands, such as 47 GHz, 60 GHz, 77 GHz, 94 GHz, and 139 GHz, are being used by taking into consideration a small size for mounting on a vehicle, high resolution, and propagation interference with existing wireless systems. In common visibility communication, a loss characteristic according to the frequencies is present with respect to air and vapor.
In weather conditions, such as rainfall or snow fall, a radio wave used in a radar for a vehicle generates considerable attenuation. The attenuation of a radio wave used in a radar for a vehicle that is generated in weather conditions, such as rainfall or snow fall, acts as an error in a radar sensor for preventing a collision, but may be used as a criterion for estimating the amount of rainfall because the attenuation is regularly increased or decreased depending on the amount of rainfall.
Recently, researches is gradually carried out on the attenuation characteristic of a radio wave for a vehicle radar in the vehicle radar application technology field and the meteorological observation field.